Motion parallax is typically a term for a perceived 3D effect which comes from having a different perspective of a scene dependent on viewing position. For example, when moving the head from side to side, the scene should be perceived differently due to the different relationships between objects. Also incorporated in this concept are other 3D cues such as lighting, shadows, binocular vision and perspective. The human visual system uses a combination of 3D cues to fully construct and perceive a 3D image.
Motion parallax provides a different image to the viewer depending on the perspective of the viewer. This is more complex than stereo vision because it is up to the viewer to determine his or her perspective, by moving around. In particular, when an observer moves, the apparent relative motion of several stationery objects against a background gives hints about a relative distance. If information about the direction and velocity of movement is known, motion parallax can provide absolute depth information. See, for example, Ferris, S. H. (1972): Motion Parallax and Absolute Distance, Journal of Experimental Psychology, 95(2), 258-263. Some methods to implement motion parallax have tracked the position of the viewer to determine the correct view for the viewer's perspective. However, these methods do not work well or at all for multiple viewers, and can exhibit latency even for a single viewer due to delays in motion tracking.
A second technique is to simultaneously show different images which appear only at the appropriate perspective—termed multi-view. Phillips® and other manufacturers have manufactured LCD displays to achieve this effect, using lenticular arrays over an LCD to direct light from certain pixels into the desired orientation. This is achieved by sacrificing image resolution—i.e., for 10 views in the horizontal direction, 10 vertical pixels for each image pixel are needed, thus degrading the horizontal resolution of the image by a factor of 10.